Adjustable pivot pneumatic control device



ATTDIMEY INVENTOR. CARL T. GU-EN c T MCLUEN 2,81 ADJUSTABLE PIVOT PNEUMATIC CONTROL DEVICE 2 Sheets-Sheet 1 ill:

Flled July 23 1956 Oct. 29, 1957 c. r. M LUEN ,8

ADJUSTABLE PIVOT PNEUMATIC CONTROL DEVICE Filed July 23, 1956 -2 Sheets-Sheet 2 INVENTOR. cm. T. M0

United States Patent ADJUSTABLE PIVOT PNEUMATIC CGNTROL DEVICE Carl T. McLuen, Milwaukee, Wis., assignor to Minneapolis-Honeyweli Regulator Company, Minneapoiis, Minm, a corporation of Delaware Application July 23, 1956, Serial No. 599,403

11 Claims. (Cl. 13785) This invention relates to pneumatic control devices and more particularly to an improved pressure actuated pilot controlled pneumatic relay.

It is an object of this invention to provide a pressure actuated control relay which is sensitive in operation and which may be readily adjusted after assembly.

It is further an object of this invention to provide a device of this type which is relatively inexpensive in construction and simple in design and which may be readily assembled and disassembled from a device with which it is normally associated.

A more specific object of this invention is to provide an improved pressure actuated relay of the force balance type having a follow-up action but with a reduction in motion of the associated parts to provide for increased accuracy and linearity of operation. Other objects will become apparent from the sepcification including the appended claims taken together with the drawings, in which:

Figure l is an exploded view of the parts of the assembled device,

Figure 2 is a schematic view of the relay,

Figure 3 is a bottom view of the cover of the device together with the actuating lever in place,

Figure 4 is a sectional view of a valve in the relay of Figure 3,

Figure 5 is a sectional view of the portion of the actuator taken along the lines 5-5 of Figure 3,

Figure 6 is a sectional view of the portion of the device taken along the lines 66 of Figure 3,

Figure 7 is a sectional view of the device taken along the lines 77 of Figure 3, and,

Figure 8 is a section view of the device shown in Figure 1.

My improved pneumatic control relay of the pilot type is best shown in the exploded view of Figure 1. The relay is housed in a two-part casing or housing one part of which a base 10 has a recessed aperture or chamber therein 11 over which it positions a cover 12 to complete the enclosure. The housing parts are held together through suitable screw means 14 embedded into tapped apertures 15 in the base part 10 to hold these parts in assembled relationship. A rubber sealing member 16 positioned in a groove 17 in the base surrounding the chamber 11 aids in sealing the chamber when the parts are in assembled relationship. Positioned within the chamber is a triangular shaped plate 20 or lever member having a pair of raised pivot surfaces 21, 22 on two sides thereof. Plate 20 is adapted to be mounted within the chamber through a pair of pivot members 31, 32 having raised surfaces 33, 34 thereon adapted to cooperate with the raised surfaces 21, 22 of the plate to provide for point type engagement between the pivots and the plate. The pivot member 31 is mounted through a sleeve 36 or spacer on an operating knob 38. Both sleeve 36 and knob 38 extend through apertures indicated at 37 and 40 in the plate 20 and cover 12 with the pivot member 31 secured to knob 38 by means of a screw 42. A small O-ring 43 is positioned in the aperture 40 in the cover overlying the sleeve or spacer 36 to seal the same. The knob 38 may adjust the pivot member 31 relative to the pivot surface 21 of the plate within a range of movement determined by a pin 45 inserted into the cover and extending to a curved type recess 46 in the cover. A similar mounting is utilized for the pivot member 32 which is mounted on an adjusting knob 48 extending through an aperture 50 from the cover and being guided by a sleeve 51 or spacer which extends along side of the plate as will be seen in Figure 3 to position the raised surface 34 of the pivot relative to the pivot surface 22 of the point. The sealing ring 53 fits into the aperture 50 of the cover overlying the spacer for sealing purposes, and the pivot member 32 is secured to the knob 48 through a screw 54. A similar limit stop is used in connection with knob 48, in the form of a pin 55 positioned in the cover and fitting into a recess 56 in the knob to limit the range of movement of the knob relative to the cover coextensive with the relative engagement of the pivot 32 with the raised surface 22 on the plate.

Cover 12 also includes a recessed area 60 in which is positioned a diaphragm 61 held in position in the recess on'a shoulder portion thereof by means of aclamping ring 62 which is secured to the cover through suitable means such as crimping (see Figures 5 and 6). Attached to the diaphragm 61 is an actuating member 65 which is secured to the diaphragm through suitable means such as a rivet type connection 68 with a washer member 69 for backing. Linkage or connection member 65 has a notch 70 therein which permits one corner of the plate 20 to be coupled to the connection member 65 as indicated in Figures 5 and 6. The raised portion 71 on the plate 20 bears against the connection member 65 to receive the thrust from the diaphragm 61 and apply the same to the plate 20. The connection member 65 extends beyond the plate and into a recess 75 in the base 10 of the casing wherein a second diaphragm 76 is positioned and suitably secured therein through means not shown. The diaphragm 76 is connected to a threaded extremity 77 of the connection member 65 with a'washer member 79 associated therewith for backing. The lower surface of the diaphragm 76 is adapted to be exposed to atmosphere and to be sealed by means of the screw and diaphragm from the recessed chamber 11 of the, base 10. The diaphragms 76 and 61 are of the same area, that is, the efiective portions thereof for purposes which will be later noted. Cover 12 includes a passage indicated in phantom at 80 leading to the back side of the diaphragm 61 to provide the conduit for signal pressure to the back side of the diaphragm. Passage 80 terminates in an aperture 81 in the undersurface of the cover which mates with a passage 83 in the base leading to a tapped port 85 in the edge of the cover through which signal pressure is transmitted.

Cover 12, also included an aperture 87 which houses a spring 89 enclosed in a cup-shaped housing 90 which fits into the aperture 87 and has its other extremity passing through an aperture 92 in the plate as will be best seen in Figure 5. Spring 89 will be hereinafter identified as the start spring for the relay and is adapted to apply a force to the plate 20 about the pivot formed by the pivot member 32 and surface 22 against the force of the pilot diaphragms 61, 76 in a manner to later be defined.

The third corner of the triangular shaped plate 20 has attached thereto a second spring 92 having a ball locking member 93 at one extremity thereof fitting through a notch 95 in this corner of the plate of member 20 to connect the spring to the plate. The opposite extremity of the spring 92 has a similar ball tip 96 which fits through a notch 97 in a cover 98 to connect this extremity of the spring to a cover 98. Surrounding spring 92 is an outer helical spring 100 which rests at one extremity against the periphery of the .plate 98 and at the other extremity against the flanged surface 101 in the base surrounding an aperture 102 in the base 10 through which a spring 92 extends. This arrangement of parts will best be seen in Figure 8. Spring 92 will hereinafter be identified as the range spring of the relay. It will be noted that the pivot member 31 engages the raised surface 21 of the plate 20 intermediate the connection of the spring 92 to the plate and the connection of the member 65 ofthe pilot relay to the plate. As previously indicated both the members 32 and 31 are adjustable relative to their associated pivot surfaces 22, 21 of plate 20 to vary the locus of pivot of the plate or the pivot axis of the plate between the springs and the pilot relay. This arrangementmay be best seen in Figure 3 and it will be evident that the adjustment of the pivotal points on either side of the plate with respect to the springs and the diaphragm relay will vary the moment arms for the forces applied to the plate from the springs and relay respectively. These adjustments vary the lever ratios and in eliect varies the forces of the spring bias counter-balancing the force of the pilot relay and applied to the plate to vary the effectiveness of the respective springs. Centering action of plate 29 between the pivots 21, 31 and 22, 32 is obtained through a light leaf type spring 99 (shown in Figure l) which is secured or riveted to plate 20 by rivets 103. The free extremities of spring 99 have apertures 106 which are pressed over guide pins 107 secured in cover 12 to locate the same. Apertures 108 in plate 20 are aligned with the free extremities of pins 107 to permit movement of the plate on its pivots to prevent interference therefrom.

Also positioned in cover 12 is a feed bleed valve 104 which is housed in anaperture 105 in the cover and is shown in section in Figure 4. The valve 104 is a threeway valve which controls the application of main line pressure from a passage indicated in phantom at 110 in the cover terminating in an aperture 112 which when the cover is in position on the base 10 aligns with a passage 115 in the base having a threaded inlet port 116 therein. The mainline pressure is valved through a passage 120 in a plug or seat member 121 positioned in the aperture 105 in the cover, the seat or plug being suitably secured in the cover through suitable means such as crimping. Cooperating with the valve seat is a double ended ball type valve member 122 which is urged against the valve seat in member 121 through a spring 124 as indicated in Figure 4. Main line pressure when the ball closure member 125 of the actuating mechanism 122 of the valve is open will pass through the passage 120 and into the interior of the chamber 11 in the housing. Mounted on the plate 20 is a second cylindrical valve seat member 128 having a passage 130 therein and a valve seat surface 131 with which a ball 132 at the other extremity of the valve actuator 122 cooperates to seal the passage 130 which is the outlet passage for the relay. Thus it will be seen that relative movement between the plate 20 and the cover 12 in an upward direction as indicated in Figure 4 will raise the valve member 122 and open the passage 120 while the passage 130 remains closed allowing main line air to enter into the chamber 11 of the relay. Movement of the plate 20 in the opposite direction or down as indicated in Figure 4 relative to the cover 12 will seat the ball member 125 on the valve seat 121 closing the main line passage and opening the passage 130 by separating the ball 132 from the seat portion 131 of the second seat member 128 to connect the outlet passage 130 to the interior of the chamber providing an exhaust passage for the chamber 11. The member 128 is secured to the plate through suitable means such as a crimping as indicated in Figure 4 and is located intermediate the springs 89 and 92 relative and equidistant from the pivot surfaces 21, 22 such that the valve 104 will be operated primarily on tilt of the plate about its pivotal axis but not on translational rotation. The exhaust passage of the valve is connected through a flexible tubular conduit member 135 which conduit member passes through an aperture in the cover member to vent the exhaust chamber to atmosphere.

My improved relay shown in section in Figure 8 has a threaded flange integral with the base 10 which is adapted for mounting the device on a pneumatic actuator. The flanged extremity 145 is adapted to be screwed into an aperture in the actuator (not shown) with the springs 92 and 100 extending into the aperture together with the plate 98. The spring 92 as a range control is adapted to produce a follow-up action of the movement of the operator of the pneumatic actuator with which the pneumatic relay is associated. Thus the plate 98 would normally extend in contact with and follow the movement of the diaphragm or piston of the actuator (not shown) under the influence of the spring 100 and operate to tension the spring 92 of the relay applying a force to the plate 20 to ofiset the force produced by the pilot diaphragms 61, 76. It will be noted that the one surface of each of the diaphragms 61, 76 is exposed to the interior chamber 11 and as such will have outlet pressure of the relay impressed thereon. The effective areas of the diaphragm 61, 76 being equal and the outlet pressure in the chamber 11 being imparted to the diaphragm with respect to the connection members 65 in opposed direction cancel out these forces such that the pilot diaphragm senses only the pilot pressure behind the diaphragm 61 as compared with the atmospheric pressure behind the diaphragm 76 on the lower surface of the base 10. A suitable passage on this lower surface along the base 10 connects this air chamber to atmosphere (not shown) when the pneumatic relay is mounted on an actuator.

In operation, my improved pneumatic pilot control relay is for the most part conventional. A variation in pilot pressure creates a force from the diaphragm 61 which is transmitted through the member 65 to the plate as will be seen schematically in Figure 3 to pivot the plate 20 relative to the pivotal axis formed by the pivots 21, 22, 31 and 32. Start spring 89 of the relay is the relatively stiffer spring compared 'with the range spring 92. It applies the force .in a direction opposite to the force applied by thepilot pressure to the diaphragm 61. Whenever this force overcomes the force applied by the start spring, the plate ;will'be tilted tending to open the outlet passage to the chamber 11 from the main line conduit and allow an increase in pressure. within the chamber 11. When an ac tuator is associated with the pneumatic control relay, the. pressure'in chamber 11 will be transmitted through the aperture 102 to the actuator causing the actuator to op crate. The change in position of the diaphragm or movable member of the associated actuator will vary the end position of the plate 98 and increase the tension on the range spring which will tend to bring the plate 20 back to a balance position in which the valve is in a neutral position and the passage of the outlet chamber is closed. Similarly a decrease in pilot pressure tends to permit the springs to counteract the pilot force and open the exhaust ports of the valve 104 bleeding air firom the chamber 11 to atmosphere. By adjusting the position of the pivot be tween the pilot diaphragm and the start spring toward the pilot connection member 65, the effectiveness of the start spring will be increased and the starting pressure setti'ngfor the relay will be increased requiring a greater pilot pressure to' overcome the effect of the start spring.

A change in the opposite direction will, of course, decrease the effectiveness of the start spring and permit the relay tostart operationata lower pilot pressure. Similar} ly a change in' the direction of the pivot between the range spring and thepilot relay or diaphragm in the direction ofthe connection member 65 .will increase the effective-- ness of the range spring suchthat a greater range in pilot pressure will be available in the operation of the relay. As previously indicated the valve 104 is located intermediate the springs and is so connected to the plate that rocking motion of the plate will have actually no effect on the operation of the valve. Spring 99 attached to plate 20 aids in locating the same within chamber 17 on the pivots for the plate but offer little or no resistance to the rocking action of the plate in normal operation. Thus, it will be seen that this improved control device provides a simplified arrangement for adjusting the start and range springs of a pneumatic pressure controller which is of the forced balance type requiring substantially little or no movement of the pilot diaphragm and the lever or plate 20 to operate the valve and thereby providing for greater accuracy in linearity of the operation of the apparatus.

The present disclosure is intended to be illustrative only and the scope of the invention should be determined only by the appended claims.

I claim:

1. In a pneumatic relay comprising, a housing having a recess therein and a cover member cooperating therewith to define with said housing a chamber, a triangular shaped plate positioned in said chamber, said cover including a recess and a passage leading therefrom to without said cover, a diaphragm positioned in said recess in said cover and adapted to have a pilot pressure connected to said passage, a linkage connected to said diaphragm to one corner of said triangular plate to pivot said plate upon movement of said diaphragm, a second diaphragm positioned in an aperture in said chamber having a passage to the outside of said housing and connected to said linkage member, a first spring connected between said cover and said plate to apply a bias to said plate at a second corner thereof remote from said connection of said linkage and said plate, a second spring connected to said plate at a third corner thereof and positioned within said chamber, valve means including inlet, outlet and exhaust passages positioned on said cover and having means connected to said plate to operate the same, the inlet passage of said valve means being connected through a passage in said cover to a main air supply, said outlet passage communicating with the interior of said chamber, conduit means connecting said exhaust passage through said housing to the atmosphere, said valve means being adapted to be operated upon tilt of said armature, a first adjustable pivot means mounting said plate on one side thereof, said pivot means being mounted in said cover and adapted to adjust the locus of pivot of said plate between one of said springs and said linkage, a second adjustable pivot means mounting said plate at a second side thereof and adapted to adjust the locus of pivot of said plate between the second of said springs and said linkage, and conduit means in said housing connected to said chamber and adapted to be connected to a pneumatic actuator to be operated thereby.

2. in a pneumatic relay comprising, a housing having a recess therein and a cover member cooperating therewith to define with said housing a chamber, a triangular shaped plate positioned in said chamber, said cover including a recess and a passage leading therefrom to without said cover, a diaphragm positioned in said recess in said cover and adapted to have a pilot pressure connected to said passage, a linkage connected to said diaphragm to one corner of said triangular plate to pivot said plate upon movement of said diaphragm, a second diaphragm positioned in an aperture in said chamber having a passage to the outside of said housing and connected to said linkage member, a first spring connected between said cover and said plate to apply a bias to said plate at a second corner thereof remote from said connection of said linkage and said plate, a second spring connected to said plate at a third corner thereof and positioned within said chamber, valve means including inlet, outlet and exhaust passages positioned on said cover and having means connected to said plate to operate the same, the inlet passage of said valve means being connected through a passage in said cover to a main air supply, said outlet passage communicating with the interior of said chamber, conduit means connectingsaid exhaust passage through said housing to the atmosphere, said valve means being adapted to be operated upon tilt of said armature, a first adjustable pivot means mounting said plate on one side thereof, said pivot means being mounted in said cover and adapted to adjust the locus of pivot of said plate between one of said springs and said linkage, a second adjustable pivot means mountsaid plate at a second side thereof and adapted to adjust the locus of pivot of said plate between the second of said springs and said linkage, conduit means in said housing connected to said chamber and adapted to be connected to a pneumatic actuator to be operated thereby, and adjustment knob means connected respectively to said first and second adjustable pivot means and positioned on the exposed surface of said cover to adjust the location of said pivots relative to said plate to vary the effects of said springs in the balance of said plate against the force supplied by said signal pressure diaphragm.

3. In a pneumatic relay, a two-part housing having a chamber therein, a triangular shaped lever means positioned in said chamber, pressure responsive means mounted in one part of saidhousing and connected to a corner of said triangular shaped lever means, conduit means adapted to be connected to a source of signal pressure and connected to said pressure responsive means for operating the same to displace said lever, a first spring connected between the part of said housing and said lever at the second corner thereof and adapted to apply a bias to said lever, a second spring positioned in said chamber. and connected to a third corner of said lever, valve means mounted on one part of said housing and connected to said lever, said valve means having an inlet, an outlet and exhaust passages, means included in part-of said housing and adapted to be connected to a source of pneumatic pressure and connected to said inlet passage of said valve means, second means included in the part of said housing and connected to said exhaust passage to provide a conduit from said exhaust passage to a point outside of said housing, said outlet passage of said relay being exposed to the chamber, a pair of adjustable pivot arms mounted on part of said housing and engaging said lever means on two sides of said lever means intermediate said springs and said pressure responsive means to pivot said plate at two points in response to the forces applied by said springs and said pressure responsive means, and adjustment means connected with said pivot means and positioned in part on said housing to vary the locus of pivot of said lever at the two sides thereof.

4. In a pneumatic relay, a two-part housing having a chamber therein, a triangular shaped lever means positioned in said chamber, pressure responsive means mounted in one part of said housing and connected to a cor ner of said triangular shaped lever means, conduit means adapted to be connected to a source of signal pressure and connected to said pressure responsive means for operating the same to displace said lever, a first spring connected between the part of said housing and said lever at the second corner thereof and adapted to apply a bias to said lever, a second spring positioned in said chamber and connected to a third corner of said lever, valve means mounted on one part of said housing and connected to said lever, said valve means having an inlet, an outlet and exhaust passages, means included in part of said housing and adapted to be connected to a source of pneumatic pressure. and connected to said inlet passage of said valve means, second means included in the part of said housing and connected to said exhaust passage to provide a conduit from said exhaust to point outside of said housing, said outlet passage of said valve means being exposed to the chamber, a pair of adjustable pivot arms mounted to the part of said housing and engaging said lever means on two sides of said lever means intermediate said springs and said pressure responsive means to pivot said plate at two points in response to the forces applied by said springs and said pressure responsive means, and adjustment means connected with said pivot means and positioned in part on said housing to vary the locus of pivot of said lever at the two sides thereof, and means connected to said second spring and operative in proportion to the pressure within said chamber to adjust the bias of said second spring applied to said lever.

5. In a pneumatic relay, a two-part housing having a chamber therein, a triangular shaped lever means positioned in said chamber, pressure responsive means mounted in one part of said housing and connected to a corner of said triangular shaped lever means, conduit means adapted to be connected to a source of signal pressure and connected to said pressure responsive means for operating the same to displace said lever, a first spring connected between the part of said housing and said lever at the second corner thereof and adapted to apply a bias to said lever, a second spring positioned in said chamber and connected to a third corner of said lever, valve means mounted on one part of said housing and connected to said lever, said valve means having an inlet, an outlet and exhaust passages, means included in part of said housing and adapted to be connected to a source of pneumatic pressure and connected to said inlet passage of said valve means, second means included in the part of said housing and connected to said exhaust passage to provide a conduit from said exhaust passage to a point outside of said housing, said outlet passage of said valve means being exposed to the chamber, an adjustable pivot means contacting said lever and points respectively between each of said springs and said pressure responsive means to vary the locus of pivot of said lever and hence the efiect of the springs of said plate in balancing said plate against the force from said pressure responsive means, and adjustment knobs connected to said adjustable pivot means and positioned in part on said housing remote from said chamber.

6. In a pneumatic relay, a two-part housing having a chamber therein, a triangular shaped lever means positioned in said chamber, pressure responsive means mounted in one part of said housing and connected to a corner of said triangular shaped lever means, conduit means adapted to be connected to a source of signal pressure and connected to said pressure responsive means for operating the same to displace said lever, a first spring connected between the part of said housing and said lever at the second corner thereof and adapted to apply a bias to said lever, a second spring positioned in said chamber and connected to a third corner of said lever, valve means mounted on one part of said housing and connected to said lever, said valve means having an inlet, an outlet and exhaust passages, means included in part of said housing and adapted to be connected to a source of pneumatic pressure and connected to said inlet passage of said valve means, second means included in the part of said housing and connected to said exhaust passage to provide a conduit from said exhaust passage to a point outside of said housing, said outlet passage of said valve means being exposed to the chamber, adjustable pivot means contacting said lever and points respectively between each of said springs and said pressure responsive meansto vary the locus of pivot of said lever and hence the effect of the springs of said plate in balancing said plate against the force from said pressure responsive means, adjustment knobs connected to said adjustable pivot means and positioned in part on said housing remote from said chamber, and means connected to said second spring and operative in proportion to the pressure within said chamber to adjust the bias of said second spring applied to said lever.

' 7. A pneumatic relay comprising, a two-part casing having a chamber therein, a triangular shaped lever member positioned in said chamber, pressure responsive means mounted on one part of said casing and exposed to said chamber, means for connecting a source of signal pressure to said pressure responsive means, linkage means connecting said pressure responsive means to one extremity of said lever member, first pivot means mounted in one part of said housing and engaging said lever on one side thereof, a second pivot means mounted in said one part of said housing and engaging said lever on a second side thereof, said two sides of said lever extending to-, ward oneanother and the connection of said pressure responsive means to said lever, a first spring having a high spring rate positioned between said one part of said housing and said lever and connected to said lever on one of said sides and remote from said pressure responsive means, a second spring means having a lesser spring rate and connected to said lever at the second side thereof and remote from said pressure responsive means valve means positioned on one part of said housing and having outlet means connected to said chamber, an inlet and exhaust means for said valve means being adapted to be connected to a source of pressure and said atmosphere respectively, a passage in one part of said housing connected to said chamber and adapted to be connected to the working chamber of a pneumatic actuator, means connected to said second spring at the extremity remote from said lever and adapted to respond to the operation of said pneumatic actuator to vary the tension of said second spring in response to movement of said actuator, and adjustable means positioned in said housing and operative from without said housing being connected to said first and second pivots to vary the position thereof relative to said side of said lever to vary the efiect of said springs on said lever in balancing the force on said lever from said pressure responsive means.

8. A pneumatic relay comprising a two-part casing having a chamber therein, a triangular plate positioned in said chamber and having ridges along two sides thereof, a pair of pivot means positioned in one part of said casing and engaging said ridges on the two sides of said triangular plate to pivot the same, pressure responsive means mounted in one part of said casing and connected to said plate at one corner thereof such that the forces applied from said pressure responsive means will pivot said plate above both of said pivots, a first spring means positioned in one part of said casing and connected to a second corner of said plate to apply a force thereto about one of said pivot means, a second spring means connected to said plate at the remaining corner thereof and adapted to apply a force to said plate above the second of said pivot means, means mounted on said second spring to vary the tension thereof in proportion to air pressure in said chamber, valve means positioned in part of said casing and in part on said plate at a point remote from said pressure responsive means, said valve means having inlet, outlet and exhaust ports, conduit means connecting said inlet port to a source of said air pressure, said exhaust port through said casing to the atmosphere and said outlet port to the interior of said chamber, said casing means having a passage therethrough to said chamber and adapted to be connected to a device to be controlled thereby with the control air passing through said passage in said casing, and means connected to said pivot means to vary the position of said pivot means along said ridges.

9. In a pneumatic relay, a two-part housing having a chamber therein, lever means positioned in said chamber, said lever means having two pivot surfaces on the converging sides thereof, pivot means positioned in one part of said casing and adapted to engage said lever means on said pivot surfaces of the two sides, pressure responsive means mounted in part on one part of said casing and connected to said lever means at an extremity near the converging sides of said lever means, said pressure responsive means being adapted to apply a force to said lever means about both of said pivots, first spring means positioned in one part of said casing and connected to said lever means at one diverging extremity thereof to apply force to said lever means against the force of said pressure responsive means about one of said pivots, second spring means connected to said lever means at the opposite side of said lever at the other diverging extremity to apply a force to said lever means opposite to said pressure responsive means and about said second pivot, valve means positioned in part on one part of said casing and gonnected to said lever means at a point remote from said pressure means and equidistantly spaced from said spring means, said valve means having inlet, outlet and exhaust passages, conduit means connecting the inlet passage of said valve means to a source of pneumatic pressure, the outlet passage of said valve means to said chamber and the exhaust passage of said valve means through said casing to atmosphere, means connected to said second spring for positioning the extremity thereof remote from said lever means in proportion to the pressure in said chamber, and means for adjusting the pivot means along the pivot surfaces of said lever.

10. In a pneumatic relay, a casing means having a chamber therein, lever means positioned in said chamber and having two pivot surfaces thereon, pivot means mounted in said casing and engaging said pivot surfaces of said lever for pivotally mounting the same on two sides thereon, first means responsive to a signal pressure connected to one extremity of said lever means and adapted to apply a force to said lever means, a pair of spring biasing means connected to the other extremity of said lever means and separated from one another to align respectively with said two pivot surfaces and said first means to give rotational and tilting movement to said lever means, valve means connected to said lever means and operated thereby, and adjustment means connected to said pivots to move the same along the surfaces of said lever to vary the application of bias from said respective springs.

11. In a pneumatic relay, a casing means having a chamber therein, lever means positioned in said chamber and having two pivot surfaces thereon, pivot means mounted in said casing and engaging said pivot surfaces of said lever for pivotally mounting the same on two sides thereon, first means responsive to a signal pressure connected to one extremity of said lever means and adapted to apply a force to said lever means, a pair of spring biasing means connected to the other extremity of said lever means and separated from one another to align respectively with said two pivot surfaces and said first means to give rotational and tilting movement to said lever means, valve means mounted on said casing in said chamber, means connecting said valve means to said lever means for operation of said valve means on tilt of said lever means, said valve means having the input, output and exhaust passages adapted to be connected respectively to an air supply, the interior of said casing and through said casing to the atmosphere, said valve means controlling the pressure within said chamber of said casing, and adjustment means connected to said pivots to move the same along the surfaces of said lever to vary the application of bias from said respective springs.

No references cited. 

